When the members of the elite Baltimore Gun Club find themselves lacking any urgent assignments at the close of the Civil War, their president, Impey Barbicane, prposes that they build a gun big enough to launch a rocket to the moon. But when Barbicane's adversary places a huge wager that the project will fail and a daring volunteer elevates the mission to a "manned" flight, one man's dream turns into an international space race.